Kia Forte: Engine Control System / Heated Oxygen Sensor (HO2S)

Kia Forte 2019-2021 (BD) Service Manual / Engine Control / Fuel System / Engine Control System / Heated Oxygen Sensor (HO2S)


HO2S [Bank 1/Sensor 1] (Linear type)

Heater Resistance (Ω)
2.4 - 4.0 [20°C(68°F)]

HO2S [Bank 1/Sensor 2] (Binary type)

A/F Ratio (λ)
Output Voltage(V)
0.6 - 1.0
0 - 0.4

Heater Resistance (Ω)
Approx. 9.0 [20°C(68°F)]

Description and operation

Heated Oxygen Sensor (HO2S) consists of zirconium and alumina and is installed both upstream and downstream of the Manifold Catalytic Converter. The sensor output voltage varies in accordance with the air/fuel ratio.

The sensor must be hot in order to operate normally. To keep it hot, the sensor has a heater which is controlled by the ECM via a duty cycle signal. When the exhaust gas temperature is lower than the specified value, the heater warms the sensor tip.

Schematic diagrams
Circuit Diagram

Harness Connector

HO2S [Bank1 / Sensor 1]

HO2S [Bank1 / Sensor 2]

Repair procedures

Turn the ignition switch OFF.


Disconnect the HO2S connector.


Measure resistance between the HO2S terminals 2 and 5 [B1/S1].

Specification : 2.4 - 4.0 [20°C(68°F)]


Measure resistance between the HO2S terminals 3 and 4 [B1/S2].

Specification : Approximately 9.0 [20°C(68°F)]


Check that the resistance is within the specification.

Removal & Installation

Note that the SST (Part No.: 09392-1Y100 or 09392-2H100) is useful when removing the heated oxygen sensor.


Turn the ignition switch OFF and disconnect the battery negative (-) terminal.


Disconnect the connector (A), and then remove the sensor (B).

Heated oxygen sensor:

39.2 - 49.1 N·m (4.0 - 5.0 kgf·m, 28.9 - 36.2 lb·ft)

[Bank 1 / Sensor 1]

[Bank 1 / Sensor 2]


Install in the reverse order of removal.


Install the component with the specified torques.

Note that internal damage may occur when the component is dropped. If the component has been dropped, inspect before installing.

DON’T use a cleaner, spray, or grease to sensing element and connector of the sensor because oil component in them may malfunction the sensor performance.

Sensor and its wiring may be damaged in case of contacting with the exhaust system (Exhaust Manifold, Catalytic Converter, and so on).

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